Composite thread roll

ABSTRACT

A composite thread rolling tool assembly comprising a hub and a removable thread forming sleeve. The sleeve has flat end surfaces permitting a plurality of sleeves to be assembled on an arbor for forming the threads thereon. The sleeve is retained on the hub by a snap ring having inclined end surfaces.

United States Patent 1 1 Bedker 1 Nov. 27, 1973 1 COMPOSITE THREAD ROLL 21 Appl. No.2 232,783

1,865,575 7/1932 Locke 72/104 3,485,164 12/1969 Bosi 29/125 3,039,334 6/1962 Kohler 72/103 Primary ExaminerL0well A. Larson Attorney-D0nald P. Bush [52] U.S. C1 72/103, 29/125, 72/478 [57] ABSTRACT [51] Int. Cl B2111 3/04 A th l bl [58] Field of Search 29/125, 148.4 D; composlte mad g tOO flSSem y comprising a hub and a removable thread formlng sleeve. The 72/102, 103, 104, 199, 118, 237, 478,

1O/152 R sleeve has flat end surfaces permitting a plurality of sleeves to be assembled on an arbor for forming the [561 CM 23::: iir szaflzzcilzzzztd zsizziis UNITED STATES PATENTS p g g 2,054,182 9/1936 Unke 10/ 152 10 Claims, 3 Drawing Figures L. 1\2 30 I; .n

l COMPOSITE-THREAD ROLL BRIEF SUMMARY OF THE INVENTION The thread roll disclosed herein is intended for use on athread rolling. fixture of the kind disclosed in my prior U.S. Pat. No. 3,353,390. Prior to the present invention the thread rolls were integrally'formed' and as finished, had about the same overall configuration as the assembly disclosed herein. This required removal-of very substantial amounts of metal in machining opera"- tions, thusrepresenting ex-traexpense in waste of material as well as the the costof machining.

In accordance with the presentinvention; the thread rolling. tool isformedof two'independent integral separate portions; One portion is a thread rollinglportion-in the form of a sleeve having a thread formation in itsouter surface. The sleeve has flat end'surfacesso'thata plurality of sleeves may be assembled on a single arbor for the production of the'thread fonn'ation on the outer surfaces of the sleeves, asby milling, grinding or the like. The second portion of the tool is a hub having an endportionshaped to b'e receivedwithinth'e openingthrough the sleeve. Thehub'portionis'generally cylindrical although it isprovided atone end-with a narrow abutment flange and intermediate its endsis-provided with a' plurality of grooves, preferably of V- shaped cross-section;

As a result of separation of the threadrolling. tool into the two main portions, it' is possible to select" the material for each portion which suits the particularrequirements of operatiom rather thanselecting a mate rial which is a compromise of these properties; Moreover, the sleeves may be producedfromcommercialy available tubular stock from=whichwafers are cut and machined to provide the required configuration; The hubs'may be machined from tube stock with a mini mum or stock removal;

The portion of the hub which receives the sleeve is of generallycylindrical configuration except for the provision of a flat surface extending: across one side. The opening through the thread rolling sleeve is of matching configuration, with a flat surface whichengages the flat surface on the hub to prevent relative rotation.

The sleeve is fixed on the hub against axial'movement by the provision of an abutment flange at one end of the hub and by theme of a snap ring 'received in an annular groove in the hub adjacent a side of the sleeve. The sleeve is thus engaged between the flange and the split ring.

Preferably, the annular grooves are of V-shaped cross-section and the split ring has a cross-sectional" shape, the radially inner portion of which is of V- shaped cross-sectionto match the configuration of the groove. The outer portion of the ring is preferably'al'so of V-shaped cross-section and cooperates with-a similarly inclined peripheral portion at one side of' the sleeve which engagesthe inclined portion of the" ring. This provides a maximum dimension for the ring opposing shearing force developed" by axial thrust on the sleeve. At the same time the inclined surfaces cause the axial'thrust of the sleeve to tend to force the ring more firmly into seating engagementin the groove.

A number of grooves may be provided on each hub so as to accommodate rolls of different width. The rolls or sleeves are preferably provided with syrn'metricalim clined surfaces at opposite sides surrounding the opening therethrough so'that the rolls or sleeves may be reversed.

' BRIEF DESCRIPTION'OF THE DRAWINGS FIG. 1 is an exploded perspective view of the components making up the thread rolling tool.

FIG. 2 is an enlarged end view of the tool assembly. FIG. 3'is asection on the line 33,.FIG. 2.

DETAILED DESCRIPTION The thread rolling tool assembly comprises the three component parts illustrated in exploded relation in FIG. 1'. These parts are the roll or sleeve supporing hub 10, the thread" forming roll'orsleeve 12, andthe snap ring' T4. The partsare assembled as shownin FIG. 2 and in use, the assembly is monted ona cylindrical pin or free rotation thereon. For this purpose the hub 10 is provided with a cylindrical opening 16' which permits the tool assembly to rotate freely on the pin. As more fully disclosed in' my prior patent 3,353,390, the thread rolling tools are adaptedto be mountedin pairs in position tospanarotating work piece. In practice, the work piece may be driven in rotation by suitable mechanism such" as that provided in an automatic screw machine, andth'e thread rolling fixture may be advanced radially to cause the opposed thread rolls to engage the rotating work piece and'to move thereon toasubstantially centered position. This generally tangential movement of each thread rollwith'reference to the work piece tends to cause rotation thereof in opposite directions. This opposed rotation is superimposedon the rotation occasionedby solid engagement between the rotary thread rolling tools and the work piece.

As more fully explained in prior Bedker U.S. Pat. No. 2,70l ,4 84, gears are provided which interconnect the I two thread-rolling tools. In operation, the fixture is arranged so that one of the tools contacts the rotating work piece in'advance of the other, and is driven in rotation thereby. Rotation of this thread roll through a series of five gears, two-of which rotate on the axes of the thread rolls, drives the other thread roll in precisely timed relation until it also solidly engages the rotating work piece. At this time the two threadrolls are in exaetly'timed relation. As the fixture is advanced to cause the threadrolls to assume a position close to diametrically opposed zones on the rotating work piece,.a lost motion connection permits the differential rotation required between the thread rolls as a result of their generally tangential advance.

The providion for lost motion comprises drive means associated with the gear which is mounted in coaxial relationship with the thread roll. This drive means comprises a key extending radially across one side of the gear and the hub 10'is provided with a relatively wide radially extending drive slot 18 to receive the dirving key, the location of which is indicated in dotted lines at 20 in FIG. 3. p

The hub 10 is provided at one end with a radially extending abutment flange 22 the side of which adjacent the thread roll or sleeve 12 is inclined as indicated at 24'.

In order to retain the thread roll 12 on the hub 10 against axial displacement, the hub is provided with a pluralityof annular grooves 26. The grooves are of V- shaped cross-section and conveniently, the sides of the grooves may be inclined at angle of 45 withrespect to the axis of the hub. The rings receive a resilient snap ring 14 which as best seen in FIG. 3 is of square crosssection so that the two radially inner surfaces thereof interfit with the inclined surfaces of one of the grooves 26. The radially outer surfaces of the ring 14 are shaped so that either may conform to an inclined or beveled surface 28 formed on the thread roll or sleeve 12 directly adjacent the opening 30 therethrough.

Preferably, the thread roll or sleeve 12 is provided with beveled or inclined surfaces 28 at both sides thereof so that the roll or sleeve 12 may be reversed on the hub. Similarly, it is preferable that the two inclined or tapered surfaces at the radially inner side of the ring 14 shall be equally inclined so that the ring may also be reversed and so that no particular attention need be given to the orientation of the ring when it is assembled on the tool.

While the ring 14 is shown as of square cross-section, it will be appreciated that the inclination of the sides may differ, although the inclination of the two radially inner inclined sides should be the same and the inclination of the two radially outer inclined sides should be the same and should also be the same as the inclination of the taper provided on the flange 22, and roll surfaces 28.

In the thread rolling operation very substantial axial forces are developed and the employment of the snap ring having the configuration disclosed herein is particularly useful. In the first place, it proivdes a maximum dimension of ring in position to oppose the shearing action developed by the axial thrust on the thread roll. Secondly, the axial thrust of the thread roll, when directed to the right as seen in FIG. 3, establishes forces having inwardly acting components tending to maintain the rings firmly in their seats. Moreover, the forces developed between the thread roll and the rings are in a direction perpendicular to the opposite surface of the groove which receives the ring.

The thread roll 12 is provided on its periphery with the thread formation indicated at 32. The opening 30 through the thread roll, as best seen in FIG. 1, is made up of a cylindrical portion 34 and a flat portion 36. Similarly, the hub has a cylindrical outer surface 38 which is interrupted only by the grooves 26 and by a flat surface 50 which is shaped to engage the flat surface 36 on the roll 12.

Accordingly, the thred roll is maintained in fixed relation on the hub 10 by engagement between the abutment flange 22 and the ring 14 and by engagement between the flat surfaces 36 of the thread roll and 40 of the hub.

The present construction permits manufacture of the thread forming roll or sleeve from pre-drilled commercially available stock, simply by cutting off wafers of the proper width to accommodate the length of thread required. This of course results in substantial savings in machining and material costs. The wafers are then broached to provide the flat surfaces 36 in the interior hole.

It has further been found to be entirely satisfactory to form all thread forming rolls or sleeves fromstock having the same internal diameter as for example, 0.800 inch This of course means that all hubs may be of corresponding transverse dimensions so that a very great economy in maintaining a proper stock of parts is permitted.

Since the hub is retained and reused, it eliminates those operations that would normally have to be performed on hub portions of the previously used unitary thread rolls, such as slotting, honing, boring, etc.; again resulting in substantial savings on material and machinmg.

Since the hub, which serves as the journal rotating on a pin in the thread rolling fixture, and the thread forming rool or sleeve which actually does the work, or separate, the material and/or heat treatment provided therefor may be controlled separately so that the hub can be made from the best material and given the best heat treat for the job it has to do. Similarly, the thread forming roll or sleeve can be made from the best material and heat treated in accordance with the requirements for the thread forming which it has to do. Thus, the composite roll is characterized in that all portion thereof have the physical characteristics best suited for the requirements thereof.

Since there are no hubs or bosses on the thread forming roll or sleeve, it is possible to double or triple the number of parts that may be mounted on grinders at one time which will afford the possibility of a major reduction in grinding time.

Since the internal diameter of the sleeve is quite large and will fit a wide variety of hubs, less tooling will be required in the manufacture, such as arbors, etc. Also, the arbors of the machines used in producing the rolls, such as the arbors of grinding machines for example, can be larger than would otherwise be the case and accordingly, can be made longer without loss of rigidity, making it possible to mount still more parts on the machine at one time for a single operation.

The thread forming roll or sleeve is interchangeable with the number of difi'erent hubs and by using the appropriate hub, the assembly may be adapted for use on a variety of different thread rolling fixtures. Accordingly, the number of parts which are kept in stock may be substantially reduced, as for example, by as much as 60 -0 percent.

The retaining ring is an important part of the assembly since the axial force is a normal and necessary reaction of thread rolling and it is necessary to have a retainer that is strong and will not release or pop off during use. At the same time, it must be small because of space limitations. By using a retainer ring of square cross-section with the surfaces inclined as suggested herein at approximately 45 to the axis of the hub, a maximum thickness of the ring is provided at the shearing point and the axial force of the sleeve tends to force the retainer ring down into the groove, thus locking it in place.

Accordingly, there is not only a substantial reduction in material cost and in manufacturing cost in the production of the composite thread rolling tool of the present invention, but there is also the substantial savings which may be effected due to the fact that the thread rolls or sleeves may be fitted onto difi'erent hubs designed for different types of thread rolling fixtures. Thus, in the final analysis, a single thread roll may be adapted for any type fixture by associating it with the proper hub component.

What I claim as my invention is:

1. A thread rolling tool having a roll forming portion provided with a thread formation for rolling threads ona a work piece and an apertured hub portion fixed to said roll forming portions for mounting said tool on a thread rolling fixture, said tool being in the form of a sub-assembly applicable to and removable from a tool support as a unit, said tool consisting in its entirety of:- an elongated hub having an opening therethrough to provide for mounting the tool on a tool support, an abutment at one end, an intermediate portion adjacent said abutment having an outer roll-supporting surface, and an outer configuration beyond said roll-supporting surface from said abutment cooperable with a roll-securing member to mount a thread roll sleeve on said hub, with one side thereof located against said abutment,

a rolling forming portion in the form of a sleeve having a threaded outer surface, an opening there through conforming to the roll-supporting surface of said hub, and means acting between said rollforming portion and said hub to prevent relative rotation therebetween and to provide for rotation of said hub and roll-forming as a unit,

and a roll-securing member engaged with said outer configuration on said hub and engaged with the side of said roll-forming portion remote from the abutment on said hub to lock said roll-forming portion firmly against said abutment.

2. A tool as defined in claim 1 in which said sleeve has flat parallel end faces which permit assembly of a plurality of said sleeves in end abutment on arbors dur ing formation of the threads thereon.

3. A tool as defined in claim 1 in which said opening through said sleeve and said intermediate exterior surface of said hub are mating cylindrically shaped internal and external surfaces including mating flat surface portions providing a driving connection therebetween.

4. A thread rolling tool having a roll forming portion provided with a thread formation for rolling threads on a work piece, and an apertured hub portion fixed to said roll forming portion for mounting said tool on a thread rolling fixture, said roll forming portion and said hub portion comprising a separate integral sleeve and a separate integral hub, said sleeve having an opening threthrough shaped to receive a portion of said hub, removable means mounting said sleeve in fixed position on said hub, the means for mounting said sleeve in fixed position on said hub comprising an annular groove in the exterior surface of said hub, and a split ring received in said groove and constituting an abutment to prevent movement of said sleeve axially of said hub.

5. A tool as defined in claim 4 in which said groove is of V-shape in cross-section, and in which the radially inner surface of said ring is of a matching V-shape.

6. A tool as defined in claim 5 in which said ring is of substantially square cross-section with sides inclined at about 45 to the axis of said hub.

7. A tool as defined in claim 5 in which the radially outer side of said ring includes an inclined surface adjacent said sleeve which is straight in transverse section, and in which the surface of said sleeve adjacent the opening therethrough is inclined to interfit with the inclined surface on said ring.

8. A tool as defined in claim 5 in which said hub has an integral annular abutment at one end engageable with the adjacent side of said sleeve.

9. A tool as defined in claim 8 in which the surface of said abutment is inclined at the same angle as the said inclined surface at the radailly outer portion of said ring to provide for reversibility of said sleeve,

10. A tool as defined in claim 8 in which the surface of said abutment is inclined at the same angle as the said inclined surface at the radially outer portion of said ring, and in which the radially outer surface of said ring has the portion thereof remote from said sleeve inclind at the same angle as the angle of inclination of the surface engageable with said sleeve to provide for reversibility of said sleeve and said ring on said hub. 

1. A thread rolling tool having a roll forming portion provided with a thread formation for rolling threads ona a work piece and an apertured hub portion fixed to said roll forming portions for mounting said tool on a thread rolling fixture, said tool being in the form of a sub-assembly applicable to and removable from a tool support as a unit, said tool consisting in its entirety of: an elongated hub having an opening therethrough to provide for mounting the tool on a tool support, an abutment at one end, an intermediate portion adjacent said abutment having an outer roll-supporting surface, and an outer configuration beyond said roll-supporting surface from said abutment cooperable with a roll-securing member to mount a thread roll sleeve on said hub, with one side thereof located against said abutment, a rolling forming portion in the form of a sleeve having a threaded outer surface, an opening therethrough conforming to the roll-supporting surface of said hub, and means acting between said roll-forming portion and said hub to prevent relative rotation therebetween and to provide for rotation of said hub and roll-forming as a unit, and a roll-securing member engaged with said outer configuration on said hub and engaged with the side of said roll-forming portion remote from the abutment on said hub to lock said rollforming portion firmly against said abutment.
 2. A tool as defined in claim 1 in which said sleeve has flat parallel end faces which permit assembly of a plurality of said sleeves in end abutment on arbors during formation of the threads thereon.
 3. A tool as defined in claim 1 in which said opening through said sleeve and said intermediate exterior surface of said hub are mating cylindrically shaped internal and external surfaces including mating flat surface portions providing a driving connection therebetween.
 4. A thread rolling tool having a roLl forming portion provided with a thread formation for rolling threads on a work piece, and an apertured hub portion fixed to said roll forming portion for mounting said tool on a thread rolling fixture, said roll forming portion and said hub portion comprising a separate integral sleeve and a separate integral hub, said sleeve having an opening threthrough shaped to receive a portion of said hub, removable means mounting said sleeve in fixed position on said hub, the means for mounting said sleeve in fixed position on said hub comprising an annular groove in the exterior surface of said hub, and a split ring received in said groove and constituting an abutment to prevent movement of said sleeve axially of said hub.
 5. A tool as defined in claim 4 in which said groove is of V-shape in cross-section, and in which the radially inner surface of said ring is of a matching V-shape.
 6. A tool as defined in claim 5 in which said ring is of substantially square cross-section with sides inclined at about 45* to the axis of said hub.
 7. A tool as defined in claim 5 in which the radially outer side of said ring includes an inclined surface adjacent said sleeve which is straight in transverse section, and in which the surface of said sleeve adjacent the opening therethrough is inclined to interfit with the inclined surface on said ring.
 8. A tool as defined in claim 5 in which said hub has an integral annular abutment at one end engageable with the adjacent side of said sleeve.
 9. A tool as defined in claim 8 in which the surface of said abutment is inclined at the same angle as the said inclined surface at the radailly outer portion of said ring to provide for reversibility of said sleeve.
 10. A tool as defined in claim 8 in which the surface of said abutment is inclined at the same angle as the said inclined surface at the radially outer portion of said ring, and in which the radially outer surface of said ring has the portion thereof remote from said sleeve inclind at the same angle as the angle of inclination of the surface engageable with said sleeve to provide for reversibility of said sleeve and said ring on said hub. 